Production of metal from pulverent material by flash smelting in a vortex

ABSTRACT

THE PRESENT INVENTION PROVIDES A REACTOR FOR PROCESSING FINELY-DIVIDED ORES INCLUDING A GENERALLY RECTANGULAR FURNACE CHAMBER HAVING BATH HEATING ELEMENTS EXTENDING THROUGH THE FURNACE ROOF AND DEPENDING TOWARD THE BATH. THE HEATING ELEMENTS ARE ARRANGED IN AT LEAST ONE ROW EXTENDING LENGTHWISE OF THE CHAMBER. AT LEAST TWO REACTANTS-INJECTING HIGH VELOCITY NOZZLES ARE PROVIDED BETWEEN EACH PAIR OF HEATING ELEMENTS AND ARE DIRECTED TO ESTABLISH A FREE-STANDING VORTEX UNSUPPORTED BY THE FURNACE WALLS, WHICH VORTEX IS LOCATED BETWEEN THE RESPECTIVE PAIRS OF HEATING ELEMENTS. A CHARGING PIPE FOR DELIVERING THE FINELY-DIVIDED ORE FEEDS THROUGH THE FURNACE ROOF AND DISCHARGES INTO A ZONE BETWEEN THE HEATING ELEMENTS AND EFFECTIVELY INTO THE FREE-STANDING VORTEX. THE HEATING ELEMENTS OF ONE EMBODIMENT COMPRISE ELECTRODES AND THE HEATING ELEMENTS OF ANOTHER EMBODIMENT COMPRISE FUELFIRED BURNERS.

Feb. 16, 1971 H. l. ELVANDER ETAL 3,563,726

PRODUCTION OF METAL FROM PULVERENT MATERIAL BY FLASH SMELTING IN AVORTEX Filed Oct. '20. 1967 2 Sheets-Sheet I l/IIII/ IINVENTIORS HansIvar E/vander Erik O/o'fl R/bin Sands from m, Awmwmm FITToRNEYS.

Feb. 16; 1971 H. ELVANDER Em 3,563,726

PRODUCTION OF METAL FROM PULVERENT MATERIA BY FLASH SMELTING IN A VORTEXFiled Oct. 20. 1967 2 Sheets-Sheet 2 a. 4/. p115; L140 FUEL INVENTORSfew 01 aF/w/A/Jm/as red/w ORNI'IYS United States Patent O 3,563,726PRODUCTION OF METAL FROM PULVERENT MATERIAL BY FLASH SMElLTING IN AVORTEX Hans Ivar Eivander and Erik Olof Albin Sundstrom,

Skelleftehamn, Sweden, assignors to Boliden Aktiebolag, Stockholm,Sweden Continuation-impart of application Ser. No. 340,395, Jan. 27,1964. This application Oct. 20, 1967, Ser. No. 676,894 Claims priority,application Sweden, Jan. 31, 1963, 1,102/63 The portion of the term ofthe patent subsequent to Jan. 23, 1985, has been disclaimer] Int. Cl.CZlc 7/00; C22b 9/00; C221! 7 8 U.S. Cl. 75-10 14 Claims ABSTRACT OF THEDISCLOSURE The present invention provides a reactor for processingfinely-divided ores including a generally rectangular furnace chamberhaving bath heating elements extending through the furnace roof anddepending toward the bath. The heating elements are arranged in at leastone row extending lengthwise of the chamber. At least tworeactants-injecting high velocity nozzles are provided between each pairof heating elements and are directed to establish a free-standing vortexunsupported by the furnace walls, which vortex is located between therespective pairs of heating elements. A charging pipe for delivering thefinely-divided ore feeds through the furnace roof and discharges into azone between the heating elements and effectively into the free-standingvortex. The heating elements of one embodiment comprise electrodes andthe heating elements of another embodiment comprise fuelfired burners.

This is a continuation-in-Part of US. Ser. No. 340,395, filed Jan. 27,1964 now Pat. No. 3,365,185.

BACKGROUND The present invention relates to the continuous production ofmetals from finely-divided oxidic or sulphidic ores and moreparticularly flotation concentrates, or other dressed products, bydirectly feeding the reactants to a furnace chamber heated to reactiontemperature by electrical means, fuel-fired burners or the like.

It should be understood that the term finely divided as used herein isin reference to the normal particle size for materials found inflotation concentrates, that is, a particle size of l0400 micrometers.

The production of metals from a finely-divided charge withoutpreparatory agglomeration, roasting or reduction steps is naturallydesirable since in this way substantial simplification of the procedureand other advantages are obtained. Several methods based on thisprinciple have been developed. A characteristic of the methods based onsome form of flash smelting is that the process has been eithercompletely autogenous, i.e., the heat developed in the reaction has beensufficient to impart to the reaction products the desired temperatureand to maintain the reaction chamber at the correct temperature(possibly by preheating the reactants charged and/or by using reactiongas enriched with oxygen) or the energy demand has been satisfied by theaddition of an extra supply of heat.

In other methods not using flash smelting the finelydivided material hasbeen melted in fuel-fired or electrically heated melting furnaces.Thereupon, the molten mass may have been subjected to an oxidation orreduction treatment in the same reaction vessel or in another one. Thelatter methods are encumbered with obvious disadvantages.

In flash smelting, however, the heat generated in the reaction between,firstly sulphidic concentrates and oxidizing gas and, secondly, oxidicmaterial and a reduction agent is, in many cases, insuflicient or incertain cases negative taking into account also the unavoidableheatlosses from the reactor chamber. Therefore, in these cases, whenconducting a flash smelting process according to methods known hitherto,it has not been possible to bring the reaction products to the correcttemperature or maintain the temperature of the reaction chamber, unlessemploying some form of external heat supply. This has been effected byadditional heating or, in the case of sulphidic material, by effectingthe combustion to such an extent that the metal to be produced iscombusted during the production of heat.

BRIEF DESCRIPTION OF INVENTION The present invention provides a reactorfor processing finely-divided ores including a generally rectangularfurnace chamber having bath heating elements extending through thefurnace roof and depending toward the bath. The heating elements arearranged in at least one row extending lengthwise of the chamber. Atleast two reactant-injecting high-velocity nozzles are provided betweeneach pair of heating elements and are directed to establish afree-standing vortex unsupported by the furnace walls, which vortex islocated between the respective pairs of heating elements. A charge pipefor feeding the finely-divided ore delivers through the furnace roof anddischarges into a zone between the heating elements and effectively intothe free-standing vortex.

In the case of oxidic materials intended for the production of iron, theinvention involves a further advantage because the ability to producereaction gas within the furnace from cheap fuels such as coal breeze,peat and brown coal. The slag formed may be further reduced directly bythe introduction of solid or gaseous reducing agents into the furnace.The degree of oxidation of the slag formed from sulfidic ores iscontrolled in a corresponding manner. By injecting the gas in a mannerto form isolated vortices and charging the ore concentrate therein, thereaction will proceed within the furnace cham her and not for the mostpart in a layer adjacent to the furnace wall which is the case forinstance in cyclonesmelting known per se. For this reason the methodaccording to the invention involves reduced attacks on the walls. Toprovide the desired reaction, the temperatures of the furnace chamber aswell as the gas therein are designed to effect concentrate smelting. Theamount of oxygen supply may be controlled. The injected gas, ifnecessary, may be preheated and the material to smelt dried to anysuitable degree. The number of vortices may be varied in dependence ofthe desired output, and the injection and charging, respectively may beeffected through the furnace roof or through inlets located at a highlevel of the furnace walls. The furnace may have a rectangular, squareor circular horizontal cross-sectional area.

FIRST EMBODIMENT One embodiment of the present invention relates to thecase in which it is more advantageous from an economical or technicalpoint of view not to compensate the mini mum heat demand of the reactionby additional fuel combustion but rather to generate the additional heatrequired by electric heating. For reasons of construction, however,electrically heated furnaces have a low roof so that, within therestricted space, it is not possible without special precautions toperform the operations of drying, preheating, ignition and reactionwithin the normally re quired short period of time. t

With the present invention, it has surprisingly proved possible withinthe relatively restricted space of an electrically heated furnace toperform a production of metals from finely-divided oxidic or sulfidicores. According to the invention, the free-standing vortex is developedbetween each electrode pair, said vortex being established by injectingreaction gas at high velocity through at least two nozzles disposedwithin the furnace chamber and directed tangentially with respect to animaginary horizontal circle. The finely-divided ore is charged into thevortex or vortices. Suitable electrical heating means includeSoderberg-electrodes which provide a heat generation within the slagbath according to the resistance principle.

In addition to the great simplification of the process achieved by theapplication of the invention in the production of lead from lead sulfideconcentrate, a substantial saving of energy has been obtained. Hithertothe concentrate was sintered with partial roasting of the sulfur to formwith heat generation oxy-sulfidic intermediate products. In electricfurnace melting, a stoichiometric proportion between remaining sulfurand oxygen contained in the lead sinter was desirable for the purpose ofobtaining lead and an SO -containing gas as end products. In flashsmelting according to the inventive process, the heat which waspreviously lost in the sintering process is now transferred to theelectric furnace and there substitutes part of the electric energypreviously required, saving around 24 mW. h. per day. Furthermore, theelectric energy previously required for effecting the sinteringoperation, i.e., for the operation of blowers and other apparatus, is nolonger required. This energy saving approximates 8 mw. h. per day.

The increased amount of waste gas resulting from the inventive flashsmelting conveys an increased amount of heat from the furnace. However,this heat is recovered by an increased steam production in a waste heatboiler connected to the smelting furnace.

SECOND EMBODIMENT In the event the use of electrical energy for heatingpurposes, according to the first embodiment of the invention, is foundto be more expensive than the use of energy obtained by the combustionof solid, liquid or gaseous fuels, greater benefits may be derived fromthe second embodiment of the invention, which relates to a system forusing such fuels to effect the necessary heating of the melt.

If sulphidic or oxidic ore concentrates are flash smelted r in a commonfuel-fired furnace, wherein there is a hot smelt bed, the temperature ofthe flames (and thus the temperature of the entire furnace chamber) mustbe kept high, about 1500 C., in the exhaust gas outlet and considerablyhigher in the firing zone, because of the relatively poor transfer ofheat between flames and bed. Usually this practice results in high wearand tear on the furnace lining, which action is further amplified by thefluxing effect which the reaction product with the concentrate exerciseson the said lining material. Attempts to protect the furnace lining bycooling or possibly by replacing certain brick portions of the liningwith cooling boxes result in extraction of heat from the bed which inturn results in poor heat economy.

If air is used as a reaction and combustion gas, the quantity of exhaustgas, and thereby the quantity of circulating dust, increases andadversely affects efficiency in comparison with flash smelting inelectrically heated furnaces. This problem can be avoided by usingoxygen or oxygen-enriched air; but this then causes the disadvantage offurther elevated flame temperatures and high wear and tear on the liningof the furnace.

When producing lead by flash smelting a sulphidic concentrate, it isundesirable to reach an exhaust-gas temperature of higher than 1100 C.,because of the high degree of volatilization of the lead and leadcompounds and the resulting circulation of dust.

The solution of this problem is provided by the oxygengas/ oil burnersdeveloped during the past few years. Such burners afford an intensivelocal heating comparable with that provided by electrodes. With thesecond embodiment of the invention, substantially the same result isachieved as that when smelting with depending electrodes. Namely, anintensive local heating is achieved in the zones where the flames fromthe burners meet the slag bed and the area in the immediate vicinitythereof while the furnace lining is protected from the hot gases.

By employing the second embodiment of the present invention, it ispossible to effect the production of metal from the finely-dividedoxidic or sulphidic ores by developing one free-standing vortex betweenthe fuel heating elements by injecting the reactants at a high velocitysubstantially tangential to an imaginary horizontal circle. Thefinely-divided ore is fed into said vortex within the zone between thefuel heating elements.

Since the hot gases of combustion from the oil burners are directedstraight against the slag bed, an intensive local heating and smeltingof the slag takes place. The slag is simultaneously subjected to apowerful agitating action. In this way, the slag can be heated toapproximately 1400 C. and the temperature of the gas in the furnacechamber, at the same time, can be held at a constant level by thecooling effect that the reaction products exerts upon the gases risingfrom the bath, meeting them in counter-current and by mounting suitablecooling elements in the furnace chamber above the level of the bath. Incase of lead smelting this cooling, in addition to causing vaporizedlead products to condense and sublimate, further protects the brickwork.Thus, the furnace chamber temperature may be held at approximately 1100C. in the gas outlet.

To compensate for the increased volume of gas when using burners insteadof electrodes, the burners are operated suitably with oxygen-enrichedair or pure oxygen. Similarly, depending upon the composition of theconcentrate, it may prove necessary to replace the reaction gas in thevortices with oxygen or oxygen-enriched air.

When using a supply of additional heat in the manner described, it isthus possible according to the invention, despite the intensive localheating of the slag bath by the burners, to impart to the gas leavingthe furnace substantially the same temperature as that obtained whensmelting according to the first embodiment using suspended electrodes.This result can be accomplished by means of suitably controllingtemperature transfer, i.e., primarily by controlling the cooling of thefurnace chamber, and secondly, by increasing the oxygen used to maintainthe amount of waste gas at the same level as when heating by means ofelectrodes.

When heating the furnace chamber with fuel-fired burners, the combustionin the flames which strikes the surface of the bath can be controlled sothat reducing, neutral or oxidizing conditions can be maintained asrequired, whereby the losses of metal in the slag can be reduced.

The invention will now be illustrated in more detail with reference tothe accompanying drawings wherein like reference characters refer tolike structure and in which FIG. 1 is a horizontal view of an electricsmelting furnace adapted for flash smelting of lead concentrateaccording to the invention. FIG. 2 is a cross-sectional view of thefurnace along line II-II in FIG. 1. FIG. 3 is a detailed view showing anozzle device for creating a tornado-like vortex and feeding leadconcentrate into said vortex. FIG. 4 shows a vertical, longitudinalsection of a furnace according to a second embodiment of the inventionprovided with fuel-fed burners for smelting lead concentrate. FIG. 5shows diagrammatically a plan view of the furnace of FIG. 4.

The furnace shown in FIGS. 1 and 2 comprises a rectangular furnacechamber of small height in relation to the horizontal cross-sectionalarea of the furnace chamber and is provided with a number of heatingelectrodes 1-4, which may be Soderberg type electrodes. The electrodesextend downwardly into the furnace chamber through cooling boxes 6-9disposed on the furnace roof, said cooling boxes having conduits (notshown) for the supply and withdrawal of cooling water. The basicconstruction of the furnace is known per se and is used in leadsmelting. There is provided a number of nozzle sets arranged within thefurnace chamber for the creation of upright tornado-like air vortices.Thus, in FIG. 1, between the electrodes 1 and 2, 2 and 3, and 3 and 4,respectively, three such sets of nozzles 10-13, 1417, and 18-21,respectively, are provided. Although it is possible to develop a vortexas described with two staggered substantially parallel directed nozzles,a greater number (such as four) arranged with mutually intersectingpaths is preferred.

The nozzle device shown in FIG. 3 comprises a vertical blowpipe 22extending through the furnace roof and terminating below the roof in abend 23 of a direction such that the jet stream of air is blowngenerally tangentially in relation to an imagined horizontal circlebetween the respective electrodes. In front of the mouth of the blowpipea charging tube 24 for lead concentrate debouches at the roof level. Abranch pipe is connnected to the charging tube with one of its branches25 extending coaxially with the charging tube 24 and the other branch 26sloping at an acute angle with the vertical. The end of the branch 25 iscovered by a lid 27 which may be removed for inspection purposes. Thecharging material is introduced through the branch 26.

In flash smelting of lead concentrate an airconcentrate mixture isinjected directly into the furnace chamber through the three sets offour nozzle devices of the type illustrated in FIG. 3. The streams ofconcentrate supplied through the charging tubes 24 are caught by thecompressed air injected through the respective nozzles 23 and entrainedinto the upright vortex which, due to the tangential injection, isformed without the aid of supporting walls. The furnace is heated bymeans of the electrodes 1-4 immersed in the slag layer, wherein due tothe ohmic resistance of the slag the heat generated is sufficient tomaintain the lead and slag contained in the furnace pot in a moltenstate.

The embodiment of the invention illustrated in FIGS. 1 to 3 has merelybeen advanced as a suitable example. Thus, it is possible to introducethe lead concentrate into the vortices through the same nozzles throughwhich the air is injected. Another possibility is to provide pairs ofopposite air nozzles at the long sides of the furnace to produce uprightvortices between the electrodes, and to charge the concentrate throughan opening above the center of each vortex.

With reference to FIGS. 4 and 5, the second embodiment will now bedescribed in detail. The nozzle arrangement for the embodiment of FIGS.4 and is the same as disclosed above and as illustrated in FIG. 3herein. The streams of air are ejected generally tangentially inrelation to an imaginary horizontal circle located between respectiveheating elements. Opening out in front of the mouth of the blower tubeat roof level is a charging tube 24 intended for lead concentrate andfed by tube 100. Charging material is introduced through tube 100, thebranch 26 and charging tube 24.

When flash smelting lead concentrate an air-concentrate mixture isinjected straight into the chamber of a furnace shown in FIG. 4, throughthe three series of nozzle arrangements of the type shown in FIG. 3.Each nozzle series includes four nozzles. The furnace is heated by meansof burners 109, 110 lowered down to the slag layer 107 above the metalbath 108. The burners are water cooled and suspended through the roof102 of the furnace. The streams of concentrate passing through thecharging tubes 24 are captured by the compressed air blown in throughrespective nozzles 23 and entrained into the free-standing tornado-likevortex, created without the support of walls as a result of thetangential injection of the mixture.

The burners 109, are of a known type and each comprises an outer,double-layer metal jacket 112 through which cooling water may be passed,the water being delivered through conduit 113 and removed throughconduit 114. Extending centrally within the jacket 112 is a fuel feedtube 115. An oxygen-containing gas is passed, via a conduit 116, to thespace of annular cross section formed between the outer metal jacket 112and the central fuel tube 115. The fuel is mixed with theoxygencontaining gas at the mouth of the burner, which is directeddownwards towards the slag bath, The flame thus formed is ejectedagainst the slag bath. The burners can be fired with pulverous, liquidor gaseous fuel, e.g., carbon powder, fuel oil, generator gas or otherfuel gases, and operated on air, oxygen-enriched air or oxygen. Theburners are preferably fired with fuel oil and, according to thecomposition of the concentrate and the desired temperature, with air,oxygen-enriched air or pure oxygen and are of such construction thatthey give a limited flame but provide for an intensive local developmentof heat which causes a strong, local heating of the. slag bath, thetemperature of which thus rises considerably above the temperature inthe furnace of the chamber. By causing the burners to discharge a fewdecimeters above the surface of the slag bath, the hot gases ofcombustion of the burners are directed immediately against the slagwhich is thus subjected to a strong heating and agitating action. Inthis way the temperature of the slag will rise to approximately 1400 C.whereas the temperature of the gas in the furnace chamber can bemaintained at a safe level by suitably cooling the furnace chamber.Therefore, when smelting lead according to the invention, the gastemperature can be kept at approximately 1100 C. This low gastemperature avoids undue wear on the furnace walls as stated above.

As can be seen from FIG. 5, the burners 109, 111 are supplemented withthe burners 109', 110', in a front row and four charging tubes 24, 24'and nozzles 23 are arranged so that they inject reactants tangentiallyto an imaginary circle, whereby a vertical vortex is obtained,unsupported by the walls of the furnace.

As mentioned above, the use of burners causes an increase in hot gasesin the furnace and therefore an effective cooling of the parts of saidfurnace subjected to the strongest mechanical and chemical actions isnecessary, particularly when the burners are operated with oxygen oroxygen-enriched air. For this purpose, as disclosed in FIG. 4, theentire roof of the furnace may comprise a water-cooled sheet metalcover, or may be provided with cooling means, e.g., cooling pipesdisposed in the brickwork of the roof of the furnace, whereby the heatcan be utilized for generating steam. If necessary the walls may also becooled in a like manner.

The embodiment of theinvention as disclosed in FIGS. 4 and 5 has onlybeen described as a suitable example. For example, the lead concentratemay be introduced into the vortex through the same nozzles through whichthe air is injected. A second alternative is to arrange the air nozzlesin the long sides of the furnace, pairwise in such a manner thatstanding vortices are created between the burners and to introduce theconcentrate through an opening above the center of the vortex.

In addition to the disclosed advantages including a local heating of thecharge and slight chemical and mechanical actions on the brickworkfurnace and the possibility of operating said furnace at a higher levelof efficiency than with conventional flash smelting furnaces, aneffective agitation of the slag batch is obtained when using fuelfiredburners. Furthermore, the flame may be adjusted as necessary bycontrolling the fuel-oxygen-ratio so that it is either oxidizing,reducing or neutral. The gases, which in the case of lead smelting leavethe furnace at approximately the same temperature as when smelting withelectrodes, are laden with, inter alia, sulphide oxide and floating dustof, for instance, lead oxide, zinc oxide, or vaporized lead which can becaught in separators in a manner known per se, while the heat content ofthe exhaust gases can be recovered in a waste heat boiler or some otherform of heat exchanger.

Either the first or second embodiment of the invention, suitablymodified, may also be used for reduction of oxidic ores, for instance inreduction of iron ore concentrates, wherein the iron ore concentrate isfed into a gas vortex established by injecting hydrogen and/or carbonmonoxide containing gases, and, if necessary, admixed with solidreduction agents such as coke breeze. The reducing gas mixture may thenbe provided by injection of solid or liquid reducing agents with anoxidizing gas, preferably air. The air may be enriched with oxygen and,if desired, preheated. In the reduction operation, the iron oreconcentrate, which may be admixed with powdered coal, is fed into a gasvortex provided by the injection of the preheated hydrogen and/or carbonmonoxide containing gases.

It will be appreciated that various modifications can be made to theherein-disclosed examples of the invention without departing from thespirit and scope thereof.

What is claimed is:

1. A reactor for the production of metals from finelydivided ores,comprising a generally rectangular furnace chamber, means for heatingthe bath within the furnace chamber comprising elongated heatingelements depending into the furnace chamber and being spaced from eachother and being arranged in at least one row extending lengthwise ofsaid chamber, at least one tube for charging into said chamberfinely-divided ore to be treated, means for discharging from the chamberreduced metal, means for injecting reactants into said chambercomprising at least one set of at least two nozzles each directedgenerally tangentially to an imaginary horizontal circle within saidchamber and adapted to inject a gas at high velocity for developing atleast one upright freestanding gas vortex not supported by the walls ofthe furnace chamber, the set of nozzles for forming the upright gasvortex and the tube for charging the ore being arranged between theheating element locations and said tube being arranged to charge the oreinto the vortex established by said set of nozzles.

2. A reactor as set forth in claim 1 wherein each set of nozzlesincludes four nozzles directed in mutually intersecting paths.

3. A reactor as set forth in claim 1 wherein a plurality of said chargetubes are provided each arranged to charge in front of one of saidnozzles.

4. A reactor as set forth in claim 1 wherein a set of said nozzles isprovided between each said heating ele- 8 ment to develop afree-standing vortex therebetween and one of said charge tubes isprovided to charge ore into each of the vortices.

5. A reactor as set forth in claim 1 wherein the heating elementscomprise electrodes which extend beneath the anticipated slag surface.

6. A reactor as set forth in claim 1 wherein the heating elementscomprise fuel-fired burners extending toward the bath within the furnacechamber and said burners developing flames directed towards theanticipated slag surface.

7. A reactor as set forth in claim 6 wherein each burner extends throughthe furnace roof and depends generally vertically with its dischargeorifice directed and in proximity with the surface of the slag.

8. A method for the production of metals from finelydivided oxidic orsulphidic ores in a generally rectangular furnace chamber which isheated by a plurality of spaced heating elements aligned in thelongitudinal direction of the chamber, said heat being sutficient toeffect the reactions and the deposit of the reaction products as a melton the bottom of the furnace, the method comprising developing betweeneach pair of heating elements one freestanding vortex, unsupported bythe walls of the furnace, by injecting reactants at high velocitygenerally tangntially to an imaginary horizontal circle, and chargingfinelydivided ore into the vortices and at the same time heating theslag bath.

9. The method of claim 8 further including heating the slag bath byelectrically heating the heating elements.

10. The method of claim 8 further comprising heating the slag bath byfuel firing the heating elements with fuel selected from the groupconsisting of solid, liquid or gaseous fuel together with a gas selectedfrom the group consisting of air, oxygen-enriched air and oxygen.

11. The method of claim 8 wherein the step of charging includes chargingwith lead sulphide concentrate.

12. The method of claim 11 wherein the vortices are developed byinjecting gas selected from the group c011- sisting of air,oxygen-enriched air and oxygen.

13. The method of claim 8 wherein the reaction temperature is maintainedat such a level that metallic lead is recovered direct without passingthrough oxi-sulphidic intermediate products.

14. The method of claim 8 wherein said step of charging includescharging with oxidic ore and that the vortices are developed byinjecting gases containing reducing agents selected from the groupconsisting of hydrogen and carbon monoxide containing gases or solid andfluid carbonaceous material.

References Cited UNITED STATES PATENTS 3,365,185 1/1968 Elvander et al.-23X ALLEN B. CURTIS, Primary Examiner U.S. Cl. X.R. 7523; 266-33

